Ptenothrix delongi is a species of globular springtail found exclusively in North America.
In winter coloring, P. delongi has distinct brown polygonal patterns on a yellow background color, while in summer it tends to be much lighter, sometimes completely yellow. It is also quite large at around . The sides were mistaken for Ptenothrix maculosa, which it was misidentified as until late 2024, when a group of citizen scientists used microscopy to confirm the species' existence and its differences to the other.
Some of the yellows are almost completely patternless, or just have a line down the middle.
The main reason this species was misidentified as both Ptenothrix maculosa and Ptenothrix beta in the past was that it has only a side pattern to the photo on collembola.org, with no dorsal view, and no antenna. The result was that Ptenothrix delongi was commonly identified wrongly as Ptenothrix maculosa for over five years, before microscopy was performed on these springtails in 2024, that keyed out to Ptenothrix delongi.